<!DOCTYPE html>
<html lang="en">

<head>
   <meta charset="UTF-8">
   <meta name="viewport" content="width=device-width, initial-scale=1.0">
   <title>Document</title>
   <style>
      div {
         width: 400px;
         height: 300px;
         border: 15px solid greenyellow;
         border-image-source: url(images/border.jpg);
         border-image-slice: 165;
         border-image-width: 20px;
         border-image-repeat: round;
      }
   </style>
</head>

<body>
   <div class="box">321</div>
</body>

</html>